Comparative and Equilibrium Studies on Anionic and Cationic Dyes Removal by Nano-Alumina-Doped Catechol Formaldehyde Composite

V Karthik,Mu Naushad,J Kiruthika,N Brinda,Tansir Ahamad,P Selvakumar,N Sivarajasekar,K Balasubramani,P Megavarshini

doi:10.1155/2020/7617989

Abstract

Nano-alumina-doped catechol formaldehyde polymeric composite was prepared, characterized, and applied as an adsorbent for the removal of an anionic dye Congo red (CR) and a cationic dye SafraninO (SF), by adsorption process especially from aqueous solutions. Characterizations such as particle size distribution, zeta potential, BET, FTIR, and FESEM-EDAX were carried out for the adsorbent prepared. All experiments were conducted at the batch condition to study the effects of initial dye concentration (CR: 30–90 mg/L and SF: 10–50 mg/L), pH (2–11), temperature (25–55°C), and adsorbent dosage (0.05–0.3 g) on dye removal. The isotherm models (Langmuir, Freundlich, and Temkin) were analyzed for this adsorption work. The kinetic data obtained were analyzed by the pseudo-first-order, pseudo-second-order, Bangham, and Chien–Clayton equations. Dyes adsorption data were well fitted with the Freundlich isotherm equilibrium model and the pseudo-second-order kinetic model. Study results suggested that the nano-alumina-polymeric composite could be an effective adsorbent for anionic dye rather than cationic dye.

Highlights

Dyes are color-forming complex compounds and naturally get adsorbed over the surface of the substrate
Triethylamine acts as a catalyst, while hexamine acts as a cross-linking agent among the catechol and formaldehyde
A 3 g of polyvinyl alcohol (PVA), a stabilizing agent, and 0.5 g of aluminum oxide were added to the whitish-yellow color emulsion within 15 min and continuously heated until it turns into a crystalline state. en, the crystals were cooled by keeping them for 8 h at room temperature. e prepared crystal was washed twice with deionized water, acetone, and ethanol separately and placed in a hot air oven to remove moisture content. e dried crystals (i.e., Alumina Polymeric Composite (APC)) were made into powdered form with uniform particle size and utilized as an adsorbent for further experiments. e synthesized APC was characterized using particle size analyzer, zeta potential, BET (Brunauer–Emmett–Teller) analysis, FTIR (Fourier transform infrared spectroscopy), and FESEM-Energy Dispersive Analysis X-Ray (EDAX)

Summary

Introduction

Dyes are color-forming complex compounds and naturally get adsorbed over the surface of the substrate. The polymer composites have majorly been preferred and considered as adsorbents to remove the synthetic dyes from the sewer [23,24,25,26,27] Since it is more effective in the process, thereby, it could contribute to resolving water pollution problems [28]. Several studies have been reported on the polymeric composite adsorbents for separating the dyes from the wastewater, doping of any of the adsorbent material in a polymeric matrix followed by carbonization and activation makes polymeric composite adsorbents [29,30,31] At this stage, there is still a need of more investigations on polymeric composite adsorbents on dye removal to make this process more effective and commercial. CR, an anionic dye and SF, a cationic dye, were selected to evaluate the adsorption efficiency of prepared alumina polymeric matrix composite in the aqueous solutions [33,34,35,36]. e equilibrium data obtained were examined using different kinetic and isotherm models to understand the adsorption mechanism

Materials and Methods

Results and Discussion

Adsorption Isotherm Studies